About whatsup app for iPad

Whatsapp is owned by Facebook. Apple has nothing to do with it so it cannot release any app for the iPad. Its up to Facebook to release an App.

You can use the website version of Whatsapp on the iPad if you have a compatible phone to connect it to.(iPhone or android).

https://web.whastapp.com

There are literally thousands. Search the App Store for messenger Apps. Do note the people you message with will need to use the same App.

Otherwise, you can use the built in Messages App on the iPad to send messages to other Apple devices.

link-> Set up Messages on iPad - Apple Support